Insanity on mid-2010 13" MBP. What's happening?

[Caleb Hauge]

The title sums it up pretty well. This machine is absolutely insane. 9 months ago (late Nov. 2020) I replaced the 10 year old thermal paste because the thing was idling at like 90 C and under any sort of load it'd shoot right up to 99 C. After repasting it wouldn't work properly. I'd hit the power button, the display would light up and show a purely white background and I could hear the HDD and ODD doing stuff but that was about it. Keyboard backlight was dead, no keyboard input, as far as I could tell no trackpad input, and when I inserted USB devices they didn't do anything or get power. A USB keyboard would still have the caps lock key flash right when I hit the power button but after that there was no activity. I tried PRAM and NVRAM and SMC resets but none worked (kinda hard to do when you can't use a keyboard). I eventually gave up and used it as a parts machine until my cat spilled milk on my daily driver Dell Latitude D820 and it fried itself last Sunday. I pulled it out, hit the power button, and it worked. Boot chime, flashing folder, everything. Well, not everything. This is where it gets complicated. The trackpad doesn't work, except it does. In the boot picker it doesn't work at all but in macOS installers it half works. I can't drag the cursor but I can left click. In newer macOS (Mojave/Catalina) I can left click but I can't left click in El Capitan or below. The keyboard is similar, except it works in the boot picker and macOS installer. The only issue it has there is that it only registers keystrokes some of the time. This is an example of what the keyboard is like. Imagine this but with typing passwords or a school project. What's even more strange is that keyboard commands aren't impacted by this at all. The keyboard "works" with those problems in Mojave and Catalina but not in El Capitan and prior. The AirPort card is completely dead, not recognized at all. I've reseated literally everything in this laptop that can be reseated and all that did was waste thermal paste and time. I even removed the keyboard, which involved a whole 67 screws. Absolutely nothing has fixed this. Keep in mind this was a fully functional laptop before the thermal paste was replaced, it just ran really hot. Oh and the HDD cable tore so I'm using a 32GB SD card to boot OS X Mountain Lion.
EDIT: Forgot one detail. Before all of this happened I had 16GB of 1066MHz OWC DDR3. After this happened it stopped POSTing with all 16GB installed, I had to remove a sodimm and it always had to be the same sodimm. That sodimm appears to have marks on the contacts now that can't be cleaned off. Now I've got 12GB (8GB+4GB).

 

[B S Magnet]

The title sums it up pretty well. This machine is absolutely insane. 9 months ago (late Nov. 2020) I replaced the 10 year old thermal paste because the thing was idling at like 90 C and under any sort of load it'd shoot right up to 99 C. After repasting it wouldn't work properly. I'd hit the power button, the display would light up and show a purely white background and I could hear the HDD and ODD doing stuff but that was about it. Keyboard backlight was dead, no keyboard input, as far as I could tell no trackpad input, and when I inserted USB devices they didn't do anything or get power. A USB keyboard would still have the caps lock key flash right when I hit the power button but after that there was no activity. I tried PRAM and NVRAM and SMC resets but none worked (kinda hard to do when you can't use a keyboard). I eventually gave up and used it as a parts machine until my cat spilled milk on my daily driver Dell Latitude D820 and it fried itself last Sunday. I pulled it out, hit the power button, and it worked. Boot chime, flashing folder, everything. Well, not everything. This is where it gets complicated. The trackpad doesn't work, except it does. In the boot picker it doesn't work at all but in macOS installers it half works. I can't drag the cursor but I can left click. In newer macOS (Mojave/Catalina) I can left click but I can't left click in El Capitan or below. The keyboard is similar, except it works in the boot picker and macOS installer. The only issue it has there is that it only registers keystrokes some of the time. This is an example of what the keyboard is like. Imagine this but with typing passwords or a school project. What's even more strange is that keyboard commands aren't impacted by this at all. The keyboard "works" with those problems in Mojave and Catalina but not in El Capitan and prior. The AirPort card is completely dead, not recognized at all. I've reseated literally everything in this laptop that can be reseated and all that did was waste thermal paste and time. I even removed the keyboard, which involved a whole 67 screws. Absolutely nothing has fixed this. Keep in mind this was a fully functional laptop before the thermal paste was replaced, it just ran really hot. Oh and the HDD cable tore so I'm using a 32GB SD card to boot OS X Mountain Lion.
EDIT: Forgot one detail. Before all of this happened I had 16GB of 1066MHz OWC DDR3. After this happened it stopped POSTing with all 16GB installed, I had to remove a sodimm and it always had to be the same sodimm. That sodimm appears to have marks on the contacts now that can't be cleaned off. Now I've got 12GB (8GB+4GB).

It might go against your instinct, but try only adding one 8GB SO-DIMM (namely, the SO-DIMM which doesn’t have the marks/scoring) to the slot which didn’t have that scored/marked SO-DIMM. What you’re doing here is testing the one slot which didn’t exhibit marks/scoring. More about that momentarily.

Also, it may be worth running memtest from single-user mode (holding Cmd-S when powering on). When you run the memtest, test only one SO-DIMM in one slot at a time. This is important. It will take some time (i.e., hours), and there isn’t much to look at while it’s working. What this hopefully will help you troubleshoot is whether a SO-DIMM slot is bad, whether an SO-DIMM is bad, or whether both are bad.

I have taken apart the mid-2009 and early 2011 13-inch MacBook Pros several times (including, to replace the keyboard with all its 987,654 screws holding it to the topcase). Aside from disassembly of the clamshell iBook, this model series is the one with which I’ve had the most time/experience taking apart and fixing.

One thing which has always been an issue for me on unibody 13-inch MBPs is this:

With any disassembly comes the real chance one of the many flat cables (like HDD cable, ODD cable, trackpad, AirPort/BT cable, and so on) will fail, even when being extremely gentle with handling it. To wit, I’ve had to replace the HDD cable twice and the Airport/BT cable once (after ruling out a bad Airport/BT card). (I’ve even ripped, by accident, the flat cable responsible for the “sleep” LED.) It’s really easy to damage one of these and annoying as heck, but I’ve come to accept these cables as quasi-consumables at this point.

Also, the SO-DIMM slots on the unibody 13" MBPs are susceptible to permanent damage as a result of shock of the laptop falling or, as was my case, the end of a broomstick sliding from leaning against the wall and slamming onto the topcase while the system was running (fortunately, not hitting the glass trackpad). This shock ruined one of the RAM slots, and I have made do with that otherwise-rock-stable system with 8GB in one slot ever since (having occurred in 2013). It’s still a daily driver.

Based on the marks/scoring you’re seeing on one of the 8GB sticks, it’s possible, even probable one or both of that RAM stick and the slot from which it came is damaged. As to how the damage might have occurred, shy of a specific incident you can recall, will probably not be possible to deduce. Repair of RAM slots are difficult, and sometimes next to impossible. I don’t know what may have caused it with your laptop without at least physically looking at your laptop, but even then, it may not be possible to know. Maybe something caused a brief short along the way.

As for high heat your MBP experienced before you cleaned its innards of dust and added new paste, high heat hastens component failure (i.e., “heat is a killer”). This may have affected components like the logic board. Idle speeds of 90°C is definitely excessive (heck, anything higher than 80°C under high load is excessive for 13-inch unibody MB/MBPs).

Start with memtest first. Work from there and get back to us.